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speedo / big tire questions...

Discussion in '1st Gen. Tacomas (1995-2004)' started by benny_802, Jul 20, 2009.

  1. Jul 20, 2009 at 9:23 AM
    #1
    benny_802

    benny_802 [OP] Member

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    Ben
    brattleboro, vt
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    tacoma
    my 1999 tacoma came with bigger-than-stock tires, i think they are 265/75. the plate on the inside of the door says stock size is 225/75. i'm wondering if my speedometer reads accurately... is there a device that would change the computer so it could adjust for different tire size and how would i know if i had one? i would like to change to smaller tires to try to achieve better fuel ecomomy, but if the speedo isn't correct it will be difficult to calculate. i'm trying to figure out for myself if bigger tires give you worse mileage and by how much. my logic goes that because they are bigger, the truck goes that much farther for each revolution of the driveshaft, but the tires are heavier, so maybe it cancels out any mileage difference. any ideas??
     
  2. Jul 20, 2009 at 2:19 PM
    #2
    Siebler

    Siebler Duck Killing Machine

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    Portland, OR
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    99 5 lug LT
    TC LT Front, F67 on 12" shackle, LCE Underdrive Pulley, Flex-a-lite fan, DT headers, Super 44 muffler, 4:11's and Aussie Locker, 22 Gallon Fuel Cell, Beard seats, custom bumpers, sliders, bed cage
  3. Jul 20, 2009 at 5:42 PM
    #3
    devilsalmostfree

    devilsalmostfree Well-Known Member

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    Loudon, Tn
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    Deck plate mod, intake silencer removed, AFE Pro Dry S Air Filter, debadged, Goodyear Duratracs 265/75R16. Flowmaster knock-off muffler!
    so, would he be racking up more or less miles then it is reading?
     
  4. Jul 20, 2009 at 5:48 PM
    #4
    Siebler

    Siebler Duck Killing Machine

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    CJ
    Portland, OR
    Vehicle:
    99 5 lug LT
    TC LT Front, F67 on 12" shackle, LCE Underdrive Pulley, Flex-a-lite fan, DT headers, Super 44 muffler, 4:11's and Aussie Locker, 22 Gallon Fuel Cell, Beard seats, custom bumpers, sliders, bed cage
    He is traveling more miles than the Odometer will say.

    When I went from stock on my 99 to 30" on my truck I was going about 11 miles for every 10 the Odometer said (at least i think thats about what it was, cant remember I have since regeared an gotten larger tires).
     
  5. Jul 20, 2009 at 5:56 PM
    #5
    devilsalmostfree

    devilsalmostfree Well-Known Member

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    Loudon, Tn
    Vehicle:
    99 Tacoma 4X4, 5 spd, 2.7 ltr
    Deck plate mod, intake silencer removed, AFE Pro Dry S Air Filter, debadged, Goodyear Duratracs 265/75R16. Flowmaster knock-off muffler!
    crap, theres no telling what my actual miles r on my truck then. this stinks, i had 265/75/15's when i bought it, then went to 31/10.50's (same, right?), now im running 235/70/15's! chris4X4 told me to multiply my odometer by 9.7% to get my actual mpg. im so lost on this tire stuff, i cant understand it.
     
  6. Jul 20, 2009 at 6:00 PM
    #6
    Siebler

    Siebler Duck Killing Machine

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    Portland, OR
    Vehicle:
    99 5 lug LT
    TC LT Front, F67 on 12" shackle, LCE Underdrive Pulley, Flex-a-lite fan, DT headers, Super 44 muffler, 4:11's and Aussie Locker, 22 Gallon Fuel Cell, Beard seats, custom bumpers, sliders, bed cage
    Im in the same boat, Tats part of the modifid truck I guess.

    Since I regeared though I am now opposite, I am now racking up more miles on the Odometer than I am going due to my gears temporarily higher than they should be for my tires.
     
  7. Jul 20, 2009 at 8:10 PM
    #7
    benny_802

    benny_802 [OP] Member

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    Ben
    brattleboro, vt
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    thanks for the info, that calculator website is neat. it's just what i thought it would be, but it's nice to see it all done. soon i will get those smaller tires and do a calculation based on mileage and take into account the error i currently have with big tires. i have been getting around 20 mpg this summer, more like 15 this past winter, so i actually am getting more. (of course, i also just realized my e brake has been slightly stuck ever since i've had the truck!)
     
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